On the interstitial and substitutional distribution of Au dissolved in solid Pb

It has been proposed that Au, when dissolved in solid Pb, exists as isolated atoms (Au₁) and small clusters of two (Au₂) and four (Au₄) atoms. In this paper three sets of data are analyzed: (1) the volume change of Pb(Au) accompanying Au precipitation at room temperature, (2) the difference in lattice parameter between Pb and Pb(Au), and (3_) the equilibrium distribution of Au in Pb in a centrifugal field. On the basis of this analysis it is concluded that Au₁ is predominantly substitutional and Au in the quenched-in Au₄ state is either mostly substitutional (each Au atom occupying a former Pb site) or vacancies are created during cluster formation and survive the quench.